A relational database can include a collection of relations, frequently known as tables. A table in the relational database can include a set of data elements or values that are organized using vertical columns and horizontal rows. The table can have a specified number of columns and a variable number of rows. Each column can have a data type that defines what category of data can be stored in the column. A row of a table can include one or more data fields. Each data field can correspond to a column, and have a data type that corresponds to the data type of the column. The type of a data column can be defined by a database schema, which can be a data model that defines how data in the relational database are represented or accessed. In a modern relational database, a data field can have a data type that permits storage of data having a large size compared to size of data of other data fields. For example, multimedia data (e.g., movie clips) can be stored in a relational database.
Data in relational databases can be stored as one or more database files on a file system. In conventional implementations of relational databases, the data having a large size, including multimedia data, can be stored together with other data fields in a same database file. A minor change in one of the other data fields can cause the entire database file to be marked as changed or “dirty” for backup purposes. A database backup program, even when configured to back up the relational database incrementally (e.g., only to back up changes since last backup), can be forced to back up a large amount of data, including the multimedia data, that did not actually change but were stored in a file that was marked as “dirty.”